@article{narayanan_mahajan_bachmann_woods_dietz_2002, title={Antiphase boundaries in GaP layers grown on (001) Si by chemical beam epitaxy}, volume={50}, ISSN={["1359-6454"]}, DOI={10.1016/S1359-6454(01)00408-6}, abstractNote={We have investigated the origin of contrast features observed in coalesced GaP islands, deposited by chemical beam epitaxy on (001) Si, by high resolution transmission electron microscopy and conventional dark field electron microscopy. Our results indicate that these features are antiphase boundaries (APBs) lying on {110} planes. Image simulations have been performed to show that APBs can only be seen under specific defocus conditions in high resolution lattice images. The observed contrast is attributed to the presence of Ga–Ga and P–P wrong bonds at APBs. A model is proposed to show that the coalescence of GaP islands on the same Si terrace may not produce APBs, and the formation of such boundaries may require the presence of monoatomic steps, separating the coalescing islands.}, number={6}, journal={ACTA MATERIALIA}, author={Narayanan, V and Mahajan, S and Bachmann, KJ and Woods, V and Dietz, N}, year={2002}, month={Apr}, pages={1275–1287} }
 @article{narayanan_mahajan_sukidi_bachmann_woods_dietz_2000, title={Orientation mediated self-assembled gallium phosphide islands grown on silicon}, volume={80}, ISSN={["0141-8610"]}, DOI={10.1080/01418610008212068}, abstractNote={Abstract Evolution of gallium phosphide epitaxial islands, grown on the (001), (111), (110) and (113) surfaces of Si by chemical beam epitaxy, has been investigated by p-polarized reflectance spectroscopy, transmission electron microscopy and atomic force microscopy. The growth nucleates as faceted three-dimensional islands on the (001) and (111) Si surfaces because of the polar nature of the heterointerface which increases the interfacial energy. A more two-dimensional-like growth mode is seen on the (110) and (113) surfaces which is attributed to the absence of charge build up at the GaP—Si heterointerface for these orientations, thereby reducing the interface energy. Islands grown on (001) Si become more faceted and larger in size with increase in growth temperature. This is due to a lower incubation time and enhanced atomic mobility at high temperatures. Wurtzite GaP has been observed to coexist with the zincblende polytype in some of the islands grown on (111) Si at 560°C. Arguments have been developed to rationalize these observations.}, number={3}, journal={PHILOSOPHICAL MAGAZINE A-PHYSICS OF CONDENSED MATTER STRUCTURE DEFECTS AND MECHANICAL PROPERTIES}, author={Narayanan, V and Mahajan, S and Sukidi, N and Bachmann, KJ and Woods, V and Dietz, N}, year={2000}, month={Mar}, pages={555–572} }
 @article{woods_dietz_ito_lauko_2000, title={Real-time thickness and compositional control of Ga1-xInxP growth using p-polarized reflectance}, volume={18}, ISSN={["0734-2101"]}, DOI={10.1116/1.582469}, abstractNote={Advances in the engineering and design of advanced electro-optical materials require sensors and control strategies that allow tight control over thickness and composition of multilayered structures. In response to this demand, we developed and applied p-polarized reflectance (PR) for real-time optical characterization and control of heteroepitaxial GaP/GaInP growth under pulsed chemical beam epitaxy conditions. For closed-loop control, we applied nonlinear control algorithms (based on nonlinear Kalman filtering) that utilizes the PR signals to adjust the source flows involved in the heteroepitaxial growth of Ga1−xInxP on Si(001). A reduced order surface kinetics model has been formulated to establish the linkage between the surface reaction kinetic and its optical response. These data are linked to compute the compositional and thickness change per time unit, utilizing the monitored PR signals for validation. This allows the establishment of feedback control algorithms, able to control both the growth rate and composition of Ga1−xInxP heterostructures.}, number={4}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS}, author={Woods, V and Dietz, N and Ito, K and Lauko, I}, year={2000}, pages={1190–1195} }
 @article{dietz_woods_ito_lauko_1999, title={Real-time optical control of Ga1-xInxP film growth by p-polarized reflectance}, volume={17}, ISSN={["1520-8559"]}, DOI={10.1116/1.581811}, abstractNote={The engineering of advanced optoelectronic integrated circuits implies the stringent control of thickness and composition. These demands led to the development of surface-sensitive real-time optical sensors that are able to move the control point close to the point where the growth occurs, which in a chemical beam epitaxy process is the surface reaction layer, built up of physisorbed and chemisorbed precursor fragments between the ambient and film interface. In this context, we explored the application of p-polarized reflectance spectroscopy (PRS) for real-time monitoring and control of pulsed chemical beam epitaxy during low-temperature growth of epitaxial Ga1−xInxP heterostructures on Si(001) substrates. A reduced order surface kinetics model has been developed to describe the decomposition and growth kinetics of the involved organometallic precursors and their incorporation in the film deposition. We demonstrate the linkage of the PRS response towards the surface reaction chemistry, composition, film growth rate, and film properties. Mathematical control algorithms are applied that link the PR signals to the growth process control parameters to control the composition and growth rate of epitaxial Ga1−xInxP heterostructures.}, number={4}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Dietz, N and Woods, V and Ito, K and Lauko, I}, year={1999}, pages={1300–1306} }